\documentclass{standalone}
\usepackage{tikz}
\usepackage{ctex,siunitx}
\usepackage{tkz-euclide}
\usepackage{amsmath}
\usetikzlibrary{patterns, calc}
\usetikzlibrary {decorations.pathmorphing, decorations.pathreplacing, decorations.shapes,}
\begin{document}
\small
\begin{tikzpicture}[>=stealth,scale=0.8]
  \fill [pattern=north east lines](-.25,0) rectangle(0,5);
  \fill [gray!20] (0,0) rectangle (3,3);
  \fill [gray!20] (0,3)--(1,3)--(0,4);
  \draw [fill=white, thick](0,4) arc(180:270:1);
  \draw[thick](1,3)--(3,3);
  \draw (0,0)--(0,5);
  \fill [gray!20] (4, 0) rectangle (4.5, 5);
  \draw [fill=white, rounded corners=0.2cm](4.5, 5)--(4.5, 4)--(4,4)--(4,5);
  \draw (4, 0)--(4,5);
  \draw (4.5, 0)--(4.5,5);
\end{tikzpicture}
\end{document}